1. Field of the Invention
The present invention relates to hand brake release mechanisms for use on railway car braking systems and more particularly, to a prolonged release mechanism.
2. Description of the Related Art
Rail car hand brake mechanisms have a user wheel that is turned to rotate a drum to take up a chain attached to the rail car brake system, this allowing a user to manually engage the brakes. Hand brake mechanisms typically include a quick release mechanism, such as a handle that can be moved by a user, which allows for an immediate and full release of the hand brake. For example, movement of the handle will disengage a clutch assembly that connects the user wheel and drum, thereby the drum to freely rotate and release the brake chain. When the quick release mechanism is released, the clutch assembly reengages and the brake chain drum is reconnected to the wheel.
A major problem with hand brakes is that if the brake chain has not fully unwound, or if the motion of the rail car causes a loss of the slack in the brake chain, an inadvertent application of the rail car brakes can occur. Unintentional braking is a serious problem and can lead to overheating, the failure of the braking system, and damages truck wheels. To remedy this problem, prolonged release mechanisms have been incorporated into the hand brake to prevent the clutch from reengaging after the quick release handle has been pulled and returned to the original position. For example, U.S. Pat. No. 8,123,004 discloses a prolonged release mechanism that maintains the clutch in the disengaged position even if the quick release handle is moved back. Although the prolonged release mechanism does disengage when the user turns the hand brake wheel, the posts on the ratchet wheel that knock the mechanism out of engagement with the clutch assembly is not a robust design, and thus could be improved to ensure longevity of the system.